Here's why:

* Sulfate refers to the polyatomic ion containing sulfur and oxygen.

* (VI) indicates the oxidation state of sulfur in the ion, which is +6.

* SO₄ represents the combination of sulfur and oxygen atoms.

* ²⁻ indicates the overall charge of the ion, which is -2.

Therefore, the complete formula for a sulfate(VI) ion is SO₄²⁻.